Embedded Cap Probe

ABSTRACT

A method for installing a probe assembly in a case of a gas turbine engine is disclosed. The method may include installing a first portion of the probe assembly within a first section of the case, and installing a second portion of the probe assembly within a second section of the case. A case assembly within a gas turbine engine is also disclosed. The case assembly may include a case in at least one of a compressor and a turbine, and a probe assembly. The probe assembly may include a first portion positioned within a bore of the case, and a second portion positioned within an inset of the case, the bore having a smaller diameter than the inset.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/015,191 filed on August 30, 2013, which is a non-provisional claimingthe 35 U.S.C. §119(e) benefit of U.S. Provisional Patent ApplicationSer. No. 61/707,336 filed on Sep. 28, 2012, the contents of each ofthese applications are incorporated herein by reference thereto.

FIELD OF THE DISCLOSURE

The present disclosure is directed generally toward capacitance basedclearance probes, and more specifically toward a capacitance-basedclearance probe built into a metal surface.

BACKGROUND OF THE DISCLOSURE

Gas turbine engines typically include a compressor, a combustor, and aturbine, with an annular flow path extending axially through each.Initially, air flows through the compressor where it is compressed orpressurized. The combustor then mixes and ignites the compressed airwith fuel, generating hot combustion gases. These hot combustion gasesare then directed from the combustor to the turbine where power isextracted from the hot gases by causing blades of the turbine to rotate.

The compressor and turbine sections include multiple rotors and statorsconfigured to enable optimal operation. Gas turbine engines maintain anoptimal clearance (distance) between the tips of the rotors and anoutside diameter of a gas path within the turbine engine, and therebyprovide the conditions necessary to achieve a desired performance.

The gas turbine engine performance is validated, in part, by measuringthe blade tip clearance. In order to measure the tip clearance, one ormore tip clearance probes are installed in the outer air seal wall ofthe turbine engine. As the tip clearance probes are incorporated ontothe outer air seal of the gas turbine after the outer air seal has beenmanufactured, it is necessary to operate the outer air seal casing toaccommodate the tip clearance probe. Existing tip clearance probearrangements require the outer air seal casing to further accommodatethe housing of the tip clearance probe, thereby limiting the locationson the outer air seal that can accept the tip clearance probe andrequiring significant additional operation of the outer air seal.

SUMMARY OF THE DISCLOSURE

According to one embodiment of the present disclosure, a method forinstalling a probe assembly in a case of a gas turbine engine isdisclosed. The method may comprise installing a first portion of theprobe assembly within a first section of the case, and installing asecond portion of the probe assembly within a second section of thecase.

In another embodiment, the method may further comprise building theprobe assembly into the case by piecemeal installation of the first andsecond portions, the probe assembly not being fully assembled beforeinstallation within the case.

In another embodiment, the method may further comprise using a sealcoating to retain the probe assembly within the case.

In another embodiment, the method may further comprise preparing a borein the first section of the case, and preparing an inset in the secondportion of the case, the bore having a smaller diameter than the inset.

In another embodiment, the method may further comprise installing asleeve and a lead within the bore of the case.

In another embodiment, the method may further comprise installing anouter ceramic pad within the inset of the case.

In another embodiment, the method may further comprise adhering a sensorface to the outer ceramic pad, and adhering an inner ceramic pad to thesensor face and outer ceramic pad.

In another embodiment, the method may further comprise attaching asensor wire from the lead to the sensor face.

In another embodiment, the method may further comprise applying anabradable coating to the inner ceramic pad, outer ceramic pad, and caseto locate and maintain a position of the probe assembly within the case.

In another embodiment, the method may further comprise removing aportion of the abradable coating to accommodate an electrical field ofthe sensor face.

According to another embodiment of the present disclosure, a caseassembly within a gas turbine engine is disclosed. The case assembly maycomprise a case in at least one of a compressor and a turbine, and aprobe assembly. The probe assembly may include a first portionpositioned within a bore of the case, and a second portion positionedwithin an inset of the case, the bore having a smaller diameter than theinset.

In another embodiment, the case assembly may further comprise a coatingapplied to the second portion and the case to retain the probe assemblywithin the case.

In another embodiment, the inset may be located on an inner side of thecase, and the bore may extend from an outer surface of the case to theinset.

In another embodiment, the first portion may include a lead assembled toa sleeve, and the sleeve may be fixed to the bore.

In another embodiment, the second portion may include an outer ceramicpad fixed to the inset, a sensor face positioned within an inset of theouter ceramic pad, and an inner ceramic pad fixed to the sensor face andthe outer ceramic pad.

In another embodiment, the lead may include a sensor wire, the sensorwire attached to the sensor face.

According to yet another embodiment of the present disclosure, a methodfor retaining a probe within a case of a gas turbine engine isdisclosed. The method may comprise using a coating to retain the probewithin the case.

In another embodiment, the method may further comprise applying thecoating to inner surfaces of the probe and the case, the coatingcomposed of abradable material.

In another embodiment, the method may further comprise removing aportion of the coating to accommodate an electric field between a sensorface of the probe and a blade tip.

In another embodiment, the method may further comprise beveling an edgeof a remaining portion of the coating.

These and other aspects and features of the disclosure will become morereadily apparent upon reading the following detailed description whentaken in conjunction with the accompanying drawings. Although variousfeatures are disclosed in relation to specific exemplary embodiments ofthe invention, it is understood that the various features may becombined with each other, or used alone, with any of the variousexemplary embodiments of the invention without departing from the scopeof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional view of a gas turbine engine,according to one embodiment of the present disclosure;

FIG. 2 is an aft view of a case of the gas turbine engine of FIG. 1,according to one embodiment of the present disclosure;

FIG. 3 is a cross-sectional view at line 3-3 in FIG. 2, according to oneembodiment of the present disclosure;

FIG. 4 is a perspective view of FIG. 3, according to one embodiment ofthe present disclosure;

FIG. 5 is a side view of an enlarged portion of a probe assembly of FIG.4, according to one embodiment of the present disclosure;

FIG. 6 is a perspective view of FIG. 3 from an inner diameter (ID) ofthe case, according to one embodiment of the present disclosure;

FIG. 7 is an enlarged cross-sectional view of the probe assembly builtinto the case of FIG. 3, according to one embodiment of the presentdisclosure;

FIG. 8 is a flowchart outlining a method for installing the probeassembly of FIG. 7 within the gas turbine engine, according to oneembodiment of the present disclosure;

FIG. 9 is a perspective view of a section of the case of FIG. 3 from anID of the case, according to one embodiment of the present disclosure;

FIG. 10 is a perspective view of the case of FIG. 9 from an outerdiameter (OD) of the case, according to one embodiment of the presentdisclosure;

FIG. 11 is a side view of the case of FIG. 9, according to oneembodiment of the present disclosure;

FIG. 12 is a perspective view of an electrical lead of the capacitanceprobe of FIG. 3 brazed to a sleeve member, according to one embodimentof the present disclosure;

FIG. 13 is a cross-sectional view of the electrical lead and sleevemember of FIG. 12 showing a sensor wire, according to one embodiment ofthe present disclosure;

FIG. 14 is a perspective view of the electrical lead and sleeve memberof FIG. 12 welded to the case, according to one embodiment of thepresent disclosure;

FIG. 15 is a cross-sectional view of an outer ceramic pad adhered to thecase and arranged with respect to the electrical lead, sleeve member,and sensor wire of FIG. 14, according to one embodiment of the presentdisclosure;

FIG. 16 is a perspective view of FIG. 15 from an ID of the case,according to one embodiment of the present disclosure;

FIG. 17 is a cross-sectional view of a sensor face adhered to theceramic pad of FIG. 15, according to one embodiment of the presentdisclosure;

FIG. 18 is a perspective view of FIG. 17 from an ID of the case,according to one embodiment of the present disclosure;

FIG. 19 is a cross-sectional view of an inner ceramic pad adhered to thesensor face and ceramic pad of FIG. 17, according to one embodiment ofthe present disclosure;

FIG. 20 is a cross-sectional view of an abradable coating sprayed ontothe inner ceramic pad, outer ceramic pad, and case of FIG. 19, accordingto one embodiment of the present disclosure;

FIG. 21 is a cross-sectional view of a portion of the abradable coatingof FIG. 20 removed, according to one embodiment of the presentdisclosure; and

FIG. 22 is a perspective view of FIG. 21 from an ID of the case,according to one embodiment of the present disclosure.

While the present disclosure is susceptible to various modifications andalternative constructions, certain illustrative embodiments thereof,will be shown and described below in detail. It should be understood,however, that there is no intention to be limited to the specificembodiments disclosed, and the intention is to cover all modifications,alternative constructions, and equivalents along within the spirit andscope of the present disclosure.

DETAILED DESCRIPTION

Referring now to the drawings, and with specific reference to FIG. 1, inaccordance with the teachings of the disclosure, an exemplary gasturbine engine 20 is shown. The gas turbine engine 20 may generallycomprise a compressor section 22 where air is pressurized, a combustor24 downstream of the compressor section which mixes and ignites thecompressed air with fuel and thereby generates hot combustion gases, aturbine section 26 downstream of the combustor 24 for extracting powerfrom the hot combustion gases, and an annular flow path 28 extendingaxially through each. The gas turbine engine 20 may be used on anaircraft for generating thrust or power, or in land-based operations forgenerating power as well.

Referring now to FIGS. 2-7, with continued reference to FIG. 1, anexample case 60, such as a case surrounding the compressor section 24 orturbine section 28 of the engine 20, is shown. The case 60 circumscribesa blade array 64, which is shown in broken line form for clarity in FIG.2.

The case 60 may hold one or more probe assemblies 70, such ascapacitance based clearance probes, within respective apertures 72 ofthe case 60. For example, the probe assemblies 70 may be embedded in thecase 60. The probe assemblies 70 may include sensors 74, such ascapacitance sensors, that monitor a distance D between tips 76 of bladeswithin the array 64 and the sensor 74. The distance D is monitoredduring operation of the engine 20. Identifying changes in the distance Dis useful as is known and may identify areas having unacceptable wearand/or performance. The sensors 74 may be linked to a controller 78 thatcalculates the distance D based on the measured capacitance.

Each of the probe assemblies 70 may include an electric lead 80, whichmay connect the sensor 74 to the controller 78, or to any other systemthat is operable to receive and act upon sensor measurements, includingvia wireless communications. In an embodiment, the sensor 74 maycomprise a sensor wire 82 extending from the lead 80, and a tack strapor sensor face 84 connected to the sensor wire 82. The probe assembly 70may also include a sleeve 86, such as a ferrule, to locate the lead 80in place within the case 60. An outer ceramic pad 88 and an innerceramic pad 90 of the probe assembly 70 may surround sensor face 84 onthe outer and inner surfaces 92, 94, respectively, of the sensor face84, serving to insulate the sensor face 84. A seal coating 96, such asan abradable coating, may be applied to at least part of the probeassembly 70 and an inner diameter (ID) surface 98 of the case 60, inorder to create a seal with the blade array 64. The seal coating 96 mayalso serve to locate and maintain the position of the probe assembly 70within the case 60.

Referring now to FIG. 8, with continued reference to FIGS. 1-7, anexemplary flowchart outlining a method 100 for installing the probeassembly 70 within the case 60 of the engine 20 is shown. The probeassembly 70 may be built into the case 60 by piecemeal installation. Theprobe assembly 70 may not be fully assembled before installation withinthe case 60 such that portions of the probe assembly 70 are installedwithin the case 60 separately.

At a first block 102, the case 60 may be prepared. For example, as shownbest in FIGS. 9-11, a bore 122 may be cut through a first section 123 ofthe case 60, and a pocket or inset 120 may be formed in a second section121 of the case 60. The bore 122 may accommodate placement of a firstportion 125 of the probe assembly 70, such as the sleeve 86 containingthe lead 80. Extending from an outer diameter (OD) surface 124 of thecase 60 to the inset 120, the bore 122 may be sized to fit the sleeve86. The inset 120 may accommodate placement of a second portion 127 ofthe probe assembly 70, such as the outer ceramic pad 88. Formed on theID surface 98 of the case, the inset 120 may be sized to fit the outerceramic pad 88. It is to be understood that dimensions of the bore 122and inset 120 may vary depending on different portions of the probeassembly 70 installed.

For example, the bore 122 may have a smaller diameter than the inset120. In the prior art, the probe assembly was pre-assembled within ahousing prior to installation. As a result, the housing contained boththe lead 80 and the sensor face 84, which limited a size of the sensorface 84 and required a large bore in the case to accommodate the housingof the entire probe assembly. In the present disclosure, on the otherhand, the sensor face 84 may have a larger surface area and diameterthan the sleeve 86 and lead 80. Furthermore, minimal material of thecase 60 may be removed to create the bore 122 and inset 120 toaccommodate the first and second portions 125, 127 of the probe assembly70. Thus, due to the piecemeal installation method disclosed, the case60 of the present disclosure has increased structural durability,strength, and stiffness of the engine case relative to the prior art.

At a next block 104, the lead 80 may be installed into the sleeve 86, asshown best in FIGS. 12-14. For example, the lead 80 may be brazed to thesleeve 86. Other suitable techniques besides brazing, such as welding orsoldering, may certainly be possible to join the electric lead 80 to thesleeve member 86. The sleeve 86, containing the lead 80, may then beinstalled inside the bore 122 of the case 60. The sleeve 86 may beattached to the case 60 via welding, or any other suitable technique. Ifpractical, the sleeve member may be omitted and the electrical lead canbe joined directly to the case.

Next, at a block 106, the outer ceramic pad 88 may be installed withinthe inset 120 of the case 60, as shown best in FIGS. 15-16. The outerceramic pad 88 may have an aperture 126 to accommodate the sensor wire82 extending from the lead 80. The outer ceramic pad 88 may then beadhered, such as by glue, to the inset 120 of the case 60. It is to beunderstood that blocks 102-112 may be performed in a different orderthan that shown in FIG. 8. For example, block 106 can occur prior toblock 104.

Then, at a block 108, which is depicted best in FIGS. 17-18, the sensorface 84 may be installed within and adhered to a pocket or inset 128 onan inner surface 129 of the outer ceramic pad 88. Glue or other means ofadhesion may be used. The sensor face 84 may have an aperture 130aligned with or concentric to the aperture 126 in the ceramic pad 88.Extending from the lead 80, the sensor wire 82 may pass through thesleeve 86, the aperture 126 in the outer ceramic pad 88, and theaperture 130 in the sensor face 84. After the outer surface 92 of thesensor face 84 is adhered to the inset 128 of the outer ceramic pad 88,the sensor wire 82 is coiled and attached, such as via welding, to theinner surface 94 of the sensor face 84.

At a next block 110, the inner ceramic pad 90 is adhered to the sensorface 84 and the outer ceramic pad 88, as shown best in FIG. 19. Theinner ceramic pad 90 may have a pocket 132 to accommodate the sensorwire 82 in order to prevent obstruction to the sensor wire 82. The innerceramic pad 90 may be glued, or attached by other suitable means ofadhesion, to the inner surface 94 of the sensor face 84 and the innersurface 129 of the outer ceramic pad 88.

Finally, at a block 112, the seal coating 96, such as an abradablecoating, may be applied to the case 60, outer ceramic pad 88, and innerceramic pad 90, as shown best in FIG. 20-22. The coating 96 may be usedto retain the probe assembly 70 within the case 60. A portion 134 of thecoating 96 may be removed in order to accommodate an electrical field ofthe sensor face 84, while still allowing a remaining portion 136 of thecoating 96 to locate and maintain the position of the probe assembly 70within the case 60. The portion 134 of the coating 96 may be removeduntil an inner surface 138 the inner ceramic pad 90 is exposed. Theremaining portion 136 may have a chamfer 140 or beveled edge, such as,at a 45 degree angle, although other angles or no bevel is certainlypossible.

INDUSTRIAL APPLICABILITY

From the foregoing, it can be seen that the teachings of this disclosurecan find industrial application in any number of different situations,including but not limited to, gas turbine engines. Such engines may beused, for example, on aircraft for generating thrust, or in land,marine, or aircraft applications for generating power.

The described disclosure provides an inexpensive, compact and effectiveprobe assembly for a gas turbine engine. The disclosed probe assemblyallows for a large sensor face while providing a relatively smalldiameter bore for the electric lead and sleeve member in the case. Thisresults in increased structural durability, strength, and stiffness ofthe case, as well as reduced labor required to re-operate the case forinstallation of the probe assembly. In addition, the re-operationprocedures and machine tooling required for installation of the probeassembly are simple and efficient due to the arrangement and geometry ofthe parts, while requiring no assembly fixtures or installationfixtures. The disclosed probe assembly also provides the advantage offlexibility with similar parts for each stage of the compressor, whichreduces lead time. Furthermore, there is low foreign object damage riskdue to the probe assembly having a thin sensor face or tack strap.

While the foregoing detailed description has been given and providedwith respect to certain specific embodiments, it is to be understoodthat the scope of the disclosure should not be limited to suchembodiments, and that the same are provided simply for enablement andbest mode purposes. The breadth and spirit of the present disclosure isbroader than the embodiments specifically disclosed and encompassedwithin the claims appended hereto.

What is claimed is:
 1. A method for installing a probe assembly in acase of a gas turbine engine, comprising: installing a first portion ofthe probe assembly within a first section of the case; and installing asecond portion of the probe assembly within a second section of thecase, wherein the probe assembly has a capacitance sensor that monitorsa distance D between tips of blades of an array and the capacitancesensor.
 2. The method of claim 1, further comprising building the probeassembly into the case by piecemeal installation of the first and secondportions, the probe assembly not being fully assembled beforeinstallation within the case.
 3. The method of claim 1, furthercomprising using a seal coating to retain the probe assembly within thecase.
 4. The method of claim 1, further comprising preparing a bore inthe first section of the case, and preparing an inset in the secondportion of the case, the bore having a smaller diameter than the inset.5. The method of claim 4, further comprising installing a sleeve and alead within the bore of the case.
 6. The method of claim 5, furthercomprising installing an outer ceramic pad within the inset of the case.7. The method of claim 6, further comprising adhering a sensor face tothe outer ceramic pad, and adhering an inner ceramic pad to the sensorface and outer ceramic pad.
 8. The method of claim 7, further comprisingattaching a sensor wire from the lead to the sensor face.
 9. The methodof claim 8, further comprising applying an abradable coating to theinner ceramic pad, outer ceramic pad, and case to locate and maintain aposition of the probe assembly within the case.
 10. The method of claim9, further comprising removing a portion of the abradable coating toaccommodate an electrical field of the sensor face.
 11. A case assemblywithin a gas turbine engine, comprising: a case in at least one of acompressor and a turbine; and a probe assembly including a first portionpositioned within a bore of the case, and a second portion positionedwithin an inset of the case, the bore having a smaller diameter than theinset, wherein the probe assembly has a capacitance sensor that monitorsa distance D between tips of blades of an array of the gas turbineengine and the capacitance sensor.
 12. The case assembly of claim 11,further comprising a coating applied to the second portion and the caseto retain the probe assembly within the case.
 13. The case assembly ofclaim 11, wherein the inset is located on an inner side of the case, andwherein the bore extends from an outer surface of the case to the inset.14. The case assembly of claim 11, wherein the first portion includes alead assembled to a sleeve, and wherein the sleeve is fixed to the bore.15. The case assembly of claim 14, wherein the second portion includesan outer ceramic pad fixed to the inset, a sensor face positioned withinan inset of the outer ceramic pad, and an inner ceramic pad fixed to thesensor face and the outer ceramic pad.
 16. The case assembly of claim15, wherein the lead includes a sensor wire, the sensor wire attached tothe sensor face.
 17. A method for retaining a probe within a case of agas turbine engine, comprising: using a coating to retain the probewithin the case, wherein the probe has a capacitance sensor thatmonitors a distance D between tips of blades of an array and thecapacitance sensor.
 18. The method of claim 17, further comprisingapplying the coating to inner surfaces of the probe and the case, thecoating composed of abradable material.
 19. The method of claim 18,further comprising removing a portion of the coating to accommodate anelectric field between a sensor face of the probe and a blade tip. 20.The method of claim 19, further comprising beveling an edge of aremaining portion of the coating.